Centralize requestId parsing to fix NumberFormatException risks across all RPC handlers

Prompted by github-code-quality review comments on PR #185
(#185 (comment)).

The bot flagged four instances of uncaught `NumberFormatException` from
`Long.parseLong(requestId)` in the new `handleExitPlanModeRequest` and
`handleAutoModeSwitchRequest` handlers. The recommended fix was to parse
`requestId` once, catch `NumberFormatException`, and reuse the parsed `long`.

Assessment: The `NumberFormatException` comments (r3221146107, r3221146111,
r3221146120, r3221146133) are fully addressed and exceeded — the fix
applies the pattern to ALL seven handlers in the class, not just the two
new ones. A shared `parseRequestId(String, String)` utility method replaces
both the flagged inline calls and an existing ad-hoc try/catch in
`handleSystemMessageTransform`.

Two additional comments (r3221146142, r3221146149) flagged the `invocation`
parameter as unused in `AutoModeSwitchHandler` and `ExitPlanModeHandler`. These
are intentionally not addressed: the parameter is part of the consistent
two-arg handler API contract shared by all handler functional interfaces
in the SDK.

--- Per-file manifest ---

`src/main/java/com/github/copilot/sdk/RpcHandlerDispatcher.java`
  - Add `private static parseRequestId(String, String)` utility that wraps
    `Long.parseLong` in a try/catch for `NumberFormatException`, logs on
    failure, and returns `-1` as a sentinel.
  - `handleToolCall`: parse `requestId` upfront via `parseRequestId`; replace
    five `Long.parseLong(requestId)` call sites with `requestIdLong`.
  - `handlePermissionRequest`: same pattern; replace three call sites.
  - `handleUserInputRequest`: same pattern; replace three call sites.
  - `handleExitPlanModeRequest`: same pattern; replace three call sites.
    (Directly addresses the linked review comment.)
  - `handleAutoModeSwitchRequest`: same pattern; replace three call sites.
  - `handleHooksInvoke`: same pattern; replace three call sites.
  - `handleSystemMessageTransform`: replace existing inline try/catch NFE
    block with the shared `parseRequestId` call, removing duplicated logic.

`src/site/markdown/advanced.md`
  - Add `.setOnPermissionRequest(PermissionHandler.APPROVE_ALL)` to the
    exit-plan-mode and auto-mode-switch code examples so they compile
    and run without a missing-handler error.

`src/test/java/com/github/copilot/sdk/ModeHandlersTest.java`
  - Parameterize `configureAuthenticatedUser(String testName)` to call
    `ctx.configureForTest("mode_handlers", testName)` with per-test
    snapshot names.
  - `shouldInvokeAutoModeSwitchHandlerWhenRateLimited`: switch from
    `sendAndWait` to `send`, add assertions on the returned `messageId`.

`src/test/java/com/github/copilot/sdk/SessionEventHandlingTest.java`
  - Update `SessionStartEventData` constructor calls (arity 10 -> 11) for
    new `detachedFromSpawningParentSessionId` field.
  - Update `AssistantMessageEventData` constructor calls (arity 12 -> 15)
    for new `anthropicAdvisorModel`, `turnId`, `parentToolCallId` fields;
    adjust positional `null` arguments accordingly.

Signed-off-by: Ed Burns <edburns@microsoft.com>

Author: edburns

src/test/java/com/github/copilot/sdk/ModeHandlersTest.java

@@ -132,8 +132,9 @@ void shouldInvokeAutoModeSwitchHandlerWhenRateLimited() throws Exception {
                             }))
                     .get(30, TimeUnit.SECONDS);
 
-            var messageId = session.send(new MessageOptions()
-                    .setPrompt("Explain that auto mode recovered from a rate limit in one short sentence."))
+            var messageId = session
+                    .send(new MessageOptions()
+                            .setPrompt("Explain that auto mode recovered from a rate limit in one short sentence."))
                     .get(30, TimeUnit.SECONDS);
 
             assertNotNull(messageId);